It is known to entrain air and other gases into ice cream to reduce its density and to soften the product. For example, ice cream freezers are known having an agitator so that the ice cream is churned as it is frozen, to entrain air. A disadvantage arises from this system, in that the high shear to which the product is subjected during this process can cause product breakdown in a manner analogous to milk turning into butter as it is churned.
Another known machine of the prior art carries a five gallon container of the unfrozen ice cream mix in such a manner that the container is rocked back and forth, while pressurized nitrous oxide is added to the ice cream mix. A disadvantage of this system, as well as of the previously described system, is that the control of the "overrun" is difficult, with large variations occurring from batch to batch. The term "overrun" refers to the amount of gas which becomes entrained in the ice cream mix to increase its volume. A frozen ice cream product with an overrun of 55% or 60% is a typical "soft serve" ice cream.
By this invention, a technique is provided for introducing a compatible, overrun-producing gas into ice cream mixes with greater accuracy for the final overrun produced, so that product variability is minimized. In the ice cream business, there is a significant need to keep the overrun constant, in that in many operations ice cream is dispensed into the cone or dish by weight. If the overrun is low on a given lot, compared with a previous lot, the volume of the same weight of ice cream will be less. This can create nonuniformity in retail delivery.